Power Supply design examples, switching

What happens if Vsw < VD In fact that is the situation in most commercial Flybacks. But note that to do a proper comparison, you have to reflect the diode drop to the primary side. And for that we have to multiply the diode drop by the turns ratio (see the equivalent Buck-Boost models of a Flyback section in my book, Switching Power Supply Design Optimization). So, for example, if the turns ratio is 20 and the diode drop is 0.6V, the effective VD we need to compare with Vsw for our time-sharing analysis is 0.6 x 20 = 12V. And that is usually greater than the (average) drop across the switch. Therefore, we tend to say that in a Flyback, decreasing D (increasing input) will worsen the total conduction loss and decrease the efficiency. But of course that never happens, because as we increase the... 

An assembly is an integrated set of components and/or subassemblies that comprise a defined part of a subsystem, for example, the pilot s radar display console or the fuel injection assembly of an aircraft propulsion subsystem. An assembly can also be composed of a number of parts, subassemblies, or any combination thereof joined together to perform a specific function and which can be disassembled without destruction of designed use (i.e., they can be reassembled). Typical examples of assemblies are power supplies, memory boards, switching devices, and so on. An assembly would be reflected as a specific level in a system hierarchy. 

The following examples, though tedious, should provide a good insight into the design process of a PWM switching power supply. 

This design example purposely avoids the use of a highly integrated buck controller IC. It would be instructional to show the selection and design process involved in a switching power supply. Refer to Figure 3-65... 

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